While the development of pharmaceutical drugs is important for continued improvement of therapeutic alternatives, pharmaceutical drug delivery methods can also play a crucial role in making drugs readily available to patient populations. The easier a therapeutic drug is to administer, the more interested a potential patient will be in the drug, thereby resulting in greater compliance with taking the drug. For example, transdermal patch delivery of nitroglycerin more than tripled the nitroglycerin market, because it made the benefits of this drug conveniently available to patients. Other drug delivery systems that have increased the availability of pharmaceutical drugs to patients are lozenges, topical creams and gels, oral cancer drugs, sustained release medicines, liposomes, and medical device applications, to name but a few.
Despite the advances made in other areas for novel drug delivery systems, the ophthalmic industry has lagged behind in improving the administration of drugs to users. Eye drops have been used for over 100 years for front of the eye diseases, and are still the most widely used method for administering drugs to the eye. In fact, over 95% of all ophthalmic drugs are delivered through a traditional eye drop bottle delivery system. But because drops administered from an eye drop bottle are relatively large, the instinctive blink that is provoked by the arrival of the large drop severely limits the amount of or proportion of fluid that actually contacts the target area on the eye. For example, less than 20% of a 50 μl drop may deliver effective treatment for a patient's eye, while the remainder is lost by drainage. The problem of drainage is further compounded by the natural limitations of the human eye to hold 7 μl to 12 μl before overflow occurs. This loss of expensive drug treatments is wasteful, and leads to uncertainty about the effectiveness of a treatment. For chronic users of certain ophthalmic drugs, this problem of overflow can also cause allergic reactions to the eyelid or in some cases staining of the skin surrounding the eye.
Another problem with overdosing the eye is systemic uptake of the drug as excess flows through the nasolacrimal duct to the back of the throat and potentially into the nasal cavity and stomach. For certain drugs such as beta blockers, undesirable systemic uptake can cause adverse respiratory or cardiac side effects. Thus, this traditional method of ophthalmic drug delivery, while affording a measure of simplicity for the user, has a number of problems, including waste and cost arising from errors in drug administration; over or under dosing arising from inexact administration of the drug; the need for preservatives in the drug to protect the efficacy of the drug once the dropper bottle is opened and exposed to air; eye irritation from exposure to preservatives required to maintain drug shelf life; loss of sterility or cross contamination of the drug; waste arising from discarding partially used bottles of the drug; accidental injury to the eye during administration; and no easy means of tracking compliance to the prescribed use of the drug. Still another disadvantage of conventional eye-droppers is that the amount of substance dispensed with an eye-dropper will depend on the amount of force the user applies to the eyedropper bottle, which presents an uncontrolled variable into the administration of a substance to the eye.
Ophthalmic drug delivery systems have been difficult to develop primarily because the eye has natural protective barriers, and is particularly sensitive to devices, implants and compounds that deliver drugs to the eye. Within the past decade, there have been a limited number of new device technologies developed that attempt to treat “front of the eye” disorders and diseases. These devices have been largely limited to reservoir based pump dropper systems that claim to maintain the sterility of the drug after the package has been opened. The commercial success of these systems is limited because they do not meet the critical challenge of making drug administration to the eye simple, precise and convenient. There is a market need for an effective multiple unit dose delivery system for ophthalmic drug administration, as evidenced by a study conducted by Beta Research Corporation, Syossett, N.Y., of a single unit dose administration using a first generation device to administer an ophthalmic drug to the front of the eye as an alternative to eye drops.
Another important consideration for the continued development of drug delivery systems is our aging population, and the increased care that people in this category need over time. For example, there are approximately 11.5 million people in nursing and assisted care centers in the U.S., and 59% need their medication administered by an assistant, taking up valuable resources, and depriving these people of their independence. As a result, there is a need for a comprehensive solution for certain patient populations, for example the elderly or those who are incapacitated, to self-administer pharmaceutical drugs in an easy and correct way. Some of the challenges facing institutional healthcare environments with respect to the administration of ophthalmic drugs to patients and residents include the time spent by caregivers administering eye drops to patients; potential liability as a result of accidental eye injuries which occur from faulty administration; increased cost due to waste; effective ophthalmic drug administration to uncooperative elderly and pediatric patients; cross contamination arising from using large institutional eye drop bottles; and the rising cost of drugs. Thus, an effective solution for addressing the shortcomings of using eye drop bottle delivery systems is needed.